THE ORIGIN OF GARDEN PLANTS AND THE FSU CONTRIBUTION

The descriptions of plants given here form only the first introduction
to the rich world of ornamentals from northeastern Eurasia. Future
studies depend on contributions that have already been done and on the
richness of the flora. It is important to know what role has Russia
played in world horticulture, how many Russian species there are among
the garden plants. This preliminary estimation can be based on comparison
of Russian and other regions’ contributions.

The number of ornamentals used by horticulturists far exceeds the total
number of species and varieties of all other known economically useful
plants. It is practically impossible to establish their exact numbers
since new cultivars appear constantly in all corners of the globe,
and there is no existing universally accepted system to register them
promptly and permanently. It is possible, however, to get an approximate
count of the number of plant species. Preliminary calculations reveal
that there are about eight thousand species of ornamentals available in
commercial trade catalogues today.

This total of garden plants can be divided into three groups. The
first consists of species from which cultivars appear most frequently in
trade catalogues and are considered commercial stock. All species
belonging to this group have many cultivars, sometimes tens of thousands,
as of the most popular garden plants such as Gladiolus, Iris,
Narcissus, Rosa, Tulipa etc. and are grown over large areas. But at
the same time, the actual number of species in this group is not great.
For instance, most of cultivars of herbaceous plants that are grown
outdoors in the Temperate zone arise from only about 120 perennial and
100 annual species. The most popular of the perennials are: peony, phlox,
iris, lily, tulip and daffodil. Among the annuals the greatest diversity
can be found in the China aster (Callistephus chinensis),
Petunia, and marigolds (Tagetes spp.). Similarly, among
the woody plants, the Rose, Rhododendron, and Clematis are
exceptional in their diversity of form.

Apart from the commercial stock, there is a second group of woody and
herbaceous species that, though cultivated to a much lesser extent,
frequently occur in our gardens and parks. These plants display less
diversity in their cultivated forms than the aforementioned group. The
two groups, together, cover about 5,000 species. A third group of about
3,000 species are mentioned in only a few trade catalogues. Among them
are many wild species that have been subjected to only initial selection.
All three groups consists of the species taken from different continents.

Some of the earliest reliable research on the geographical origin of
cultivated plants can be found in the work of De Candolle (1855). His
studies of 247 species of cultivated plants established that 50 of them
have a history dating back five to six thousand years. He also determined
that most of these useful plants originated in the "Old World," (Europe,
Asia and North Africa). Later on, many biologists, including Charles
Darwin, studied the history of domestic animals and plants.

The fundamental investigations regarding cultivated plant origin were
done by Russian scientist, N. I. Vavilov (1926). He made a comprehensive
study of the origin of cultivated plants, and proposed that there were
eight world centers of ancient civilization, at which the greatest
concentration of diversity in cultivated plant species and their varieties
(cultivars) occurred; unfortunately, he excluded ornamentals from his
investigation. Since then many scientists have investigated the origin of
economically useful plants as a whole and ornamentals in particular.
Among the authors who have contributed to identifying the centers of origin
of ornamental plants are: Basilevskaya (1960), who investigated the
geographical origin of garden plants; Coats (1968), who traced the history
of ornamentals, especially herbs; Fisher (1982), who described how many
ornamentals were taken from nature; and Hui-Lin Li (1974), who wrote about
the introduction of woody plants. These papers and analysis of the origin
of the 5,000 species (mentioned above) used in horticulture made it possible
to establish the centres of origin of ornamental plants. Therefore, the
regions described below have been arranged according to the geographical
distribution of the wild species of common garden plants. In many cases
Vavilov's centres were used as a base. Thirteen centers (instead of eight
for economic plants) can now be defined for ornamental plants. Although
the division into regions is a fundamental one, the fact that in this study
the bulk of ornamentals were taken into consideration allows us to regard
this divisions as reliable. The determination of the floristic regions is
based on the system proposed by Takhtajan (1978, 1986). The centers of
origin of ornamental plants presented here are given according to importance.
The contribution of each range, i.e. the number of ornamental species
discovered in each range and its proportion of the total amount of species,
has been evaluated with regard to its role in the development of the world's
resources.